This invention relates to the generation of electrical energy and has particular relationship to completely self-sufficient generators which create electrical energy in places where no other sources than such generators are available. Among the devices for which such a generator can serve as a power supply are cardiac pacemakers or heart pacers.
A heart pacer supplies electrical pulses to the heart of a patient or subject to drive the pumping muscles of the heart. The pacer includes a pulse generator embedded below the abdomen of a subject and an electrode in driving engagement with the heart. The electrode is connected to the generator through a cable. The cathode pole of the pulse supply is at the electrode; the anode pole in the generator. Each pulse is typically a square-wave pulse having a duration of about 1.5 milliseconds. Typically the pulse current is between 4 and 10 milliamperes; the load supplied by the pulses is 300 to 700 ohms paralleled by a capacitance of 0.25 microfarads and resistance of 1000 ohms. The frequency of the pulses depends on the subject and typically is 70 plus or minus 5 per minute for humans and 12.0 plus or minus 5 per minute for dogs. The generator should deliver a voltage of about 6 volts. The installation of a pacer in a subject demands major surgery.
In pacemakers in accordance with the teachings of the prior art the supply is a battery of long-life cells, such as MERCURY cells. But the life of such a battery is at most 2 or 3 years and in the light of the danger to the subject of loss of battery power and the surgery required to replace batteries a much longer-life power supply is required. To overcome this disadvantage of the prior art, a generator is provided which includes a central radioactive fuel capsule about which is wound spirally, fabric having embedded therein strands of thermocouple material. Foil of heat radiation reflecting material and of insulation are wound between the layers of fabric. Typically, the fabric may be formed by spinning thermal insulating thread, for example quartz thread, as woof on the thermoelectric strands as warp. The thread may be the warp and the thermoelectric strands the woof but this has the disadvantage that the relatively stiff metal strands must be turned under and over the yieldable quartz thread rather than the converse. Alternate thermoelectric strands are of opposite polarity materials and the ends of adjacent strands are conductively joined so that the opposite-polarity strands of the tape form a thermopile of long thermocouples in series.
The tape is wound so that the ends of the thermoelectric strand of the inside of the spiral are contiguous to the capsule and form the hot junction of the pile. The ends of the tape on the outside of the spiral form the cold junction.
To achieve the desired voltage which may be as high as 6 volts, it is necessary that a large number of thermocouples of the wires in the tape be connected in series for this purpose it is necessary that the hot and cold junctions be formed of the wire ends of wires of opposite thermoelectric polarity. In these junctions the wire ends must be joined in firm electrical contact and the junctions must be effectively insulated from each other. It is an object of this invention to achieve this desideration; that is, to provide an electrical component including sets of wires having terminal ends to be joined in firm electrical contact with the joined terminal ends of different sets of the wires effectively insulated from each other.